1 //===========================================
  2 // Function : Asynchronous read write RAM 
  3 // Coder    : Deepak Kumar Tala
  4 // Date     : 1-Nov-2005
  5 //===========================================
  6 module ram_sp_ar_aw #(parameter DATA_WIDTH = 8,
  7                   parameter ADDR_WIDTH = 8,
  8                   parameter RAM_DEPTH = (1 << ADDR_WIDTH))(
  9 input  wire [ADDR_WIDTH-1:0] address  , // Address Input
 10 inout  wire [DATA_WIDTH-1:0] data     , // Data bi-directional
 11 input  wire                  cs       , // Chip Select
 12 input  wire                  we       , // Write Enable/Read Enable
 13 input  wire                  oe         // Output Enable
 14 );          
 15 //--------------Internal variables---------------- 
 16 reg [DATA_WIDTH-1:0]   data_out ;
 17 // Use Associative array to save memory footprint
 18 typedef reg [ADDR_WIDTH-1:0] mem_addr;
 19 reg [DATA_WIDTH-1:0] mem [mem_addr];
 20 
 21 //--------------Code Starts Here------------------ 
 22 // Tri-State Buffer control 
 23 // output : When we = 0, oe = 1, cs = 1
 24 assign data = (cs && oe &&  ! we) ? data_out : 8'bz; 
 25 
 26 // Memory Write Block 
 27 // Write Operation : When we = 1, cs = 1
 28 always_latch
 29 begin : MEM_WRITE
 30   if ( cs && we ) begin
 31     mem[address] = data;
 32   end
 33 end
 34 
 35 // Memory Read Block 
 36 // Read Operation : When we = 0, oe = 1, cs = 1
 37 always_latch
 38 begin : MEM_READ
 39   if (cs &&  ! we && oe)  begin
 40      data_out = mem[address];
 41   end
 42 end
 43 
 44 endmodule // End of Module ram_sp_ar_aw

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